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Trial registered on ANZCTR


Registration number
ACTRN12616000041459
Ethics application status
Approved
Date submitted
12/01/2016
Date registered
19/01/2016
Date last updated
24/03/2017
Type of registration
Prospectively registered

Titles & IDs
Public title
Ultrasound assessment of cardiac output in healthy women at elective caesarean section under spinal anaesthesia with an ephedrine, metaraminol combination to prevent a fall in blood pressure.
Scientific title
Transthoracic echocardiographic assessment of cardiac output in healthy women at elective caesarean section under spinal anaesthesia with an ephedrine, metaraminol combination as hypotension prophylaxis: an observational cohort study.
Secondary ID [1] 288294 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cardiac output in healthy women having elective caesarean section under spinal anaesthesia 297255 0
Condition category
Condition code
Anaesthesiology 297458 297458 0 0
Anaesthetics
Reproductive Health and Childbirth 297459 297459 0 0
Childbirth and postnatal care

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
This is an observational study measuring the change in maternal cardiac
output ten minutes after injection of spinal anaesthetic in the presence
of intravenous ephedrine and metaraminol used to maintain systolic blood pressure within
90% of baseline.
The cardiac output will be measured by transthoracic echocardiography.
The systolic blood pressure will be monitored until delivery of the baby.
Intervention code [1] 293590 0
Not applicable
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 297020 0
The range of values for cardiac output and stroke volume.
Heart rate (HR) will be measured from a standard 3-lead ECG continuous
recording. Automated non-invasive blood pressure (NIBP) measurements
will be taken at 1 minute intervals from the commencement of the
ephedrine/metaraminol infusion with a cuff placed on the upper arm using the
oscillometric method. One-minutely NIBP and HR readings will be retrieved
post-operatively from the memory of the anaesthetic machine.
Transthoracic echocardiographic measurement of the cardiac output (CO)
and stroke volume (SV) will be determined using the following method. In
the parasternal long axis (PLAX) view, a good quality image of the left
ventricular outflow tract (LVOT) will be obtained. This is defined as an
image in which the aortic valve can be seen and the structure looks
tubular. This image is zoomed and frozen during systole and then stored.
The apical five chamber (A5C) view will then be used to ascertain the LVOT
velocity time integral (VTI). A good quality image is one with maximal
chamber size, a vertical long axis and maximal mitral valve opening size.
Pulse wave Doppler will be used with a 3 mm sample volume placed within
the LVOT approximately 0.5 cm proximal to the aortic valve. The angle of
Doppler interrogation of flow will be less than 20 degrees. At least three
consecutive beats will be recorded and the images stored. Following the
completion of the scans the images will be used to calculate the cardiac
output.
In regard to LVOT diameter the PLAX image will allow the measurement of
the LVOT diameter (in cm) perpendicularly to the aortic root from the
junction of the anterior coronary cusp and the interventricular septum to
the junction of the posterior non-coronary aortic cusp and the anterior
mitral valve leaflet.
The VTI shall be measured by tracing the leading edge of the velocity
spectrum of three consecutive beats. The VTI used to calculate CO will be
the average of these three beats. Heart rate will be measured from the
Doppler spectral display from the time between two consecutive beats in
the VTI tracing.
For calculation of SV and CO:
a) SV (ml) = [(LVOT diameter)^2 x 0.785](cm^2) x VTI(cm). (where [(LVOT)
^2 x 0.785 = p x LVOT radius^2 = cross sectional area of the LVOT)
b) CO (ml/min) = heart rate(beats/min) x [(LVOT diameter)^2 x 0.785]
(cm^2) x VTI(cm).
Timepoint [1] 297020 0
Immediately pre-spinal and 10 minutes post spinal injection.
Primary outcome [2] 297021 0
The change in cardiac output and stroke volume.
A change is measured by using change score ANOVA.
Timepoint [2] 297021 0
Immediately pre-spinal and 10 minutes post spinal injection.
Secondary outcome [1] 319868 0
The amount of ephedrine and metaraminol required to maintain systolic blood pressure to
90% of the baseline reading for each patient.
This will be calculated as the sum of the total infusion dose delivered and
the total number of boluses delivered; the values will be obtained
directly from the infusion pump memory and documented directly on the
participant study data sheet . Analysis will be descriptive; median [25th-
75th percentile].
Timepoint [1] 319868 0
This will be for the period from commencement of the ephedrine/metaraminol infusion
to time of birth of the baby.
Secondary outcome [2] 319869 0
The number of women requiring treatment for bradycardia of heart rate
less than 50 beats per minute with associated hypotension of systolic
blood pressure less than 90 mmHg.
This will be monitored and documented directly on the participant study
data sheet and presented as number and percentage.
Timepoint [2] 319869 0
Monitored and documented for the interval from commencement of
ephedrine/metaraminol infusion to birth of the baby.
Secondary outcome [3] 319870 0
Maternal side-effects – nausea and vomiting; shivering; dizziness;
headache, any others as noted and will be documented directly on the
participant study data sheet. All will be recorded by a study investigator
as either absent or present.
This will be analysed as median [25th -75th percentile]
Timepoint [3] 319870 0
Monitored continously and documented for the interval from
commencement of ephedrine/metaraminol infusion to birth of the baby.
Secondary outcome [4] 319871 0
Neonatal APGAR scores at 1 and 5 minutes.
This will be assessed as median[25th-75th percentile].
Timepoint [4] 319871 0
At 1 and 5 minutes after the birth of the baby.
Secondary outcome [5] 319872 0
Arterial and venous umbilical cord pH and lactate will be measured with automated
blood gas analyser and documented directly on the participant study
data sheet.
This will be assessed as median[25th-75th percentile].
Timepoint [5] 319872 0
Measured and documented at the birth of the baby.

Eligibility
Key inclusion criteria
Elective caesarean section
American Society of Anesthesiologists (ASA) physical status grade I or II,
Gestation greater than 37 weeks
Singleton pregnancy
Non-smoker
Minimum age
18 Years
Maximum age
40 Years
Gender
Females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Insulin dependent diabetes mellitus
Use of vasoactive medication including salbutamol, beta-blockers and thyroxine
In labour
BMI greater than 40.0

Study design
Purpose
Screening
Duration
Cross-sectional
Selection
Defined population
Timing
Prospective
Statistical methods / analysis
Demographic data will be presented as mean (SD), median [25th – 75th
percentile] and number (%) according to type and distribution. Summary
measures for primary (HR, LVOT, VTI) and derived (SV and CO) outcome
measurements will be presented for both measurement times along with
change scores for the two derived measures. These will include 95%
confidence intervals for HR, CO, CI and SV.
Assessment of compliance with mean arterial pressure control (MAP) will
be performed: (i) across all 10+ blood pressure measurements using
proportion within target interval (90 – 110% of baseline) and (ii) for the
T9-T11 (one minute each side of the T10 measurement) using a
dichotomous marker equals to 1 if all three readings lie within the target
interval.
Assessment of the relationship between HR, SV and CO will be explored
graphically.
Assessment of change in CO will be made using change score ANOVA if
change scores are approximately normally distributed or following
transformation to normality if not. A Wilcoxon sign rank test on change
scores may also be used.
Sample size calculation is based upon within patient change in cardiac
output, at a detectable difference of 600 ml, mean baseline CO 4400 ml,
two-sided significance level 0.05 and power 0.8. There is no data
available to estimate SD for the within patient change score. We used
the SD (1000 ml) found on the baseline CO data of 28 patients in
previously published work.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 5027 0
Mercy Hospital for Women - Heidelberg
Recruitment hospital [2] 5028 0
Werribee Mercy Hospital - Werribee
Recruitment postcode(s) [1] 12513 0
3084 - Heidelberg
Recruitment postcode(s) [2] 12514 0
3030 - Werribee

Funding & Sponsors
Funding source category [1] 292670 0
Hospital
Name [1] 292670 0
Mercy Hospital for Women
Address [1] 292670 0
163 Studley Road
Heidelberg
Victoria 3084
Country [1] 292670 0
Australia
Primary sponsor type
Hospital
Name
Mercy Hospital for Women
Address
163 Studley Road
Heidelberg
Victoria 3084
Country
Australia
Secondary sponsor category [1] 291391 0
None
Name [1] 291391 0
Address [1] 291391 0
Country [1] 291391 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 294142 0
Mercy Health Human Research Ethics Committee
Ethics committee address [1] 294142 0
163 Studley Road
Heidelberg
Victoria 3084
Ethics committee country [1] 294142 0
Australia
Date submitted for ethics approval [1] 294142 0
26/11/2015
Approval date [1] 294142 0
08/12/2015
Ethics approval number [1] 294142 0
R15/42

Summary
Brief summary
One of the most common types of anaesthetic used for caesarean section is a spinal anaesthetic. In order for women to be comfortable during the operation a large number of nerves are blocked. In addition to the pain nerves it is very common for other nerves to be affected, including those which are responsible for other types of sensation, movement in the legs and also those which normally help control blood pressure. Significantly low blood pressure in the mother may be associated with side-effects including nausea and vomiting, dizziness and possibly loss of consciousness and in extreme situations the baby may also receive a reduced blood supply from the placenta. For the anaesthetist to provide a safe anaesthetic it is very important to monitor these effects and especially any changes to blood pressure and how the woman’s body responds to it. This is particularly important during the first 5 to 10 minutes after the injection of the spinal anaesthetic. During this period it is usual to closely measure blood pressure, heart rate, the amount of oxygen in the blood and the electrical activity of the heart from an electrocardiogram.
Recently, it has also become possible to directly observe the function of the heart relatively quickly and easily via a hand-held ultrasound probe placed on the chest – a transthoracic echocardiogram or TTE. These devices are very similar to those used for obtaining images of the baby during pregnancy. It is known from the use of these devices in other situations, including in pregnant women, that valuable information may be obtained about how the heart is performing. Until now this has not been done in healthy women having a spinal anaesthetic for an elective caesarean section. Hence, the purpose of our study is to document the effects of a standard spinal anaesthetic on the output of the heart by comparing measurements at approximately 10 minutes after the spinal injection with measurements taken immediately before the spinal using TTE. In keeping with usual practice, drugs will be given to help maintain normal blood pressure throughout. The drugs used will be ephedrine and metaraminol..
Information obtained from this study will be helpful in further understanding the impact of spinal anaesthetics on the cardiovascular system in pregnant women which is likely to help guide anaesthetists to reduce side effects and improve safety.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 62670 0
A/Prof Scott Simmons
Address 62670 0
Mercy Hospital for Women
163 Studley Road
Heidelberg
Victoria 3084
Country 62670 0
Australia
Phone 62670 0
+61 3 8458 4113
Fax 62670 0
Email 62670 0
ssimmons@mercy.com.au
Contact person for public queries
Name 62671 0
A/Prof Scott Simmons
Address 62671 0
Mercy Hospital for Women
163 Studley Road
Heidelberg
Victoria 3084
Country 62671 0
Australia
Phone 62671 0
+61 3 8458 4113
Fax 62671 0
Email 62671 0
ssimmons@mercy.com.au
Contact person for scientific queries
Name 62672 0
A/Prof Scott Simmons
Address 62672 0
Mercy Hospital for Women
163 Studley Road
Heidelberg
Victoria 3084
Country 62672 0
Australia
Phone 62672 0
+61 3 8458 4113
Fax 62672 0
Email 62672 0
ssimmons@mercy.com.au

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary